docs: def migrate(cls, resource, datacenter_id, background=False):
          """ Migrate a disk to another datacenter. """
          disk_id = cls.usable_id(resource)
          result = cls.call('hosting.disk.migrate', disk_id, datacenter_id)
  
          if background:
              return result
  
          cls.echo('Disk migration in progress.')
          cls.display_progress(result)
          return result